圆钢管UHPC短柱轴压承载力与变形能力计算模型

An analytic model for axial load capacity and deformation capacity of short columns of circular UHPC filled steel tube

根据力的平衡和变形协调,推导出钢管折减系数和核心混凝土增强系数的解析表达式,研究圆钢管约束对超高性能混凝土(UHPC)轴压强度的增强作用和环向应力对圆钢管轴压强度的折减作用;建立圆钢管UHPC短柱轴压承载力计算模型,并与已有的规范方法进行比较;基于Mander模型,根据横向约束等效原则,建立圆钢管约束UHPC单轴受压本构模型,并利用理想弹塑性模型建立能够考虑环向应力影响的圆钢管单轴受压本构模型,实现对圆钢管UHPC短柱轴压受力全过程的模拟,并与试验结果进行比较。研究结果表明:与规范方法相比,承载力模型能够更好地兼顾计算精度和可靠度;利用变形能力计算模型得到的全过程荷载-位移曲线与试验结果较吻合。

Due to force equilibrium and deformation compatibility,the expressions of steel tube reduction coefficient and core concrete strengthen coefficient were deduced to study the improvement of confinement of steel tube on axial strength of ultra high performance concrete(UHPC)and the reduction of circumferential stress on axial strength of steel tube.Based on the above two factors,an analytic model for load capacity of circular UHPC filled steel tube stub columns was established,and the proposed model was compared with several conventional standard methods.According to the equivalence principle of transverse confinement,the axial compressive constitutive model was established for circular steel tube confined UHPC based on Mander model.Ideal elastic-plastic model was modified to take the effect of circumferential stress into account for the axial compressive constitutive model of circular steel tube.The two above models were used to simulate the axial compressive load-deformation curve of short columns with circular UHPC filled steel tube.The results show that compared with several methods given by standards,the axial load capacity model shows good calculation precision and reliability,the axial compressive load-deformation curve given by the proposed model is in good agreement with that of trial results.